43 research outputs found
The spatially-differentiated total nitrogen budget for Great Britain
To understand Nitrogen (N) cycling, mechanisms of N transformation, and factors that influence N pathway, N budgets at different scale were constructed in this thesis. This thesis addresses N cycling in Great Britain (GB) through four discrete investigations at the national to catchment scale. At the national scale, a spatially-differentiated N budget for GB was constructed at a 1 km2 grid scale, which showed that both sink and source areas exist in GB. The spatial N budget across GB ranged from -21 (±3) to 34 (±5) tonnes N/km2/yr, with 66% of grid squares identified as source areas and 34% identified as sink areas. A spatial N budget of the Trent catchment was constructed by using local rather than country level N flux data, revealing range of -16 (±5) to 32 (±6) tonnes N/km2/yr. To test where N accumulation occurred, 24 locations were selected for soil sampling to test the C/N for different soil depths. The study demonstrates that depth profile has a significant affect upon C/N ratio between sink and source under grassland, however, this measure tested for N accumulation did prove to be significant under grassland but not under arable.
Between 1990 and 2015 the temporal changes in the N budget of the Trent catchment varied from -4.3 (±0.7)×104 to 3.5 (±0.5)×104 tonnes N. N accumulation in the Trent catchment is likely continue at a similar magnitude in the future until the soil of Trent catchment reaches saturated state. The research also updates the nitrate flux model at country scale and finds that catchment area, organic soil, each land use area and gas emission, all have a positive relationship with nitrate flux whereas N deposition and rainfall, both have a negative relationship with nitrate flux
Uncovering nitrogen accumulation in a large mixed land-use catchment: Implications for national-scale budget studies and environmental management
Accurately quantifying the location and extent of nitrogen accumulation is crucial for mitigating its severe impacts on climate and the environment. Here we estimated a spatial total N budget and its input/output fluxes from different land uses on a 1 km2 grid scale across the whole of a large, mixed land use catchment (Trent, UK). With a long history of water quality monitoring, the Trent catchment provides a unique and ideal test bed for developing a detailed nitrogen budget and determining where N accumulation occurs. In 2015, a significant 35 (±5) ktonnes N accumulation was found, with 31 % of the area acting as a net source and 69 % as a net sink. The spatial budget ranged from −16 (±5) to 45 (±7) tonnes N/km2/year. Using this budget, we identified N accumulation and loss areas under diverse land uses and conducted strategic soil sampling and C/N analysis. Notably, grassland subsoil exhibited nitrogen buildup compared to arable land, spotlighting intricate land use, nitrogen, and soil dynamics. The study emphasizes the need for targeted nutrient management to prevent potential environmental repercussions linked to subsoil nitrogen accumulation, especially in grassland contexts
Efficacy and safety analysis of TACE + PEI + lenvatinib compared with TACE + lenvatinib for the treatment of hepatocellular carcinoma with PVTT: a retrospective study
ObjectiveThe aim of this study was to investigate the efficacy and safety of transcatheter arterial chemoembolization (TACE) combined with percutaneous ethanol injection (PEI) and lenvatinib in HCC patients with PVTT (Vp2-3), thus providing a safe and effective treatment strategy for advanced HCC patients.Materials and methodsClinical data of 227 patients with unresectable HCC and PVTT treated at the Union Hospital from January 2018 to December 2021 were retrospectively analyzed. The patients were divided into two groups according to their treatment methods: TACE+PEI+lenvatinib group (N=103) and TACE+lenvatinib group (N=124).ResultsThe proportion of patients with disappearance, shrinkage, or no change of PVTT after treatment was significantly higher in the TACE+PEI+lenvatinib group compared to the TACE+lenvatinib group, with statistical significance (P<0.001). The TACE+PEI+lenvatinib group had higher objective response rate (ORR) (50.5% vs. 25.8%, P<0.001) and disease control rate (DCR) (87.4% vs. 74.2%, P=0.013) than the TACE+lenvatinib group. The median progression-free survival (mPFS) of the TACE+PEI+lenvatinib group was longer than that of the TACE+lenvatinib group (8.1 months vs. 6.5 months, P<0.001). Consistently, the median overall survival (mOS) of the TACE+PEI+lenvatinib group was longer than that of the TACE+lenvatinib group (17.1 months vs. 13.9 months, P<0.001).ConclusionAmong HCC patients with PVTT (Vp2-3), TACE+PEI+lenvatinib is more effective comparing to TACE+lenvatinib in prolonging PFS and OS. The control of PVTT in the TACE+PEI+lenvatinib group was significantly more satisfactory than that in the TACE+lenvatinib group. TACE+PEI+lenvatinib is a safe and effective treatment strategy for HCC patients with PVTT (Vp2-3)
Nitrogen-enriched hierarchically porous carbon materials fabricated by graphene aerogel templated Schiff-base chemistry for high performance electrochemical capacitors
This article presents a facile and effective approach for synthesizing three-dimensional (3D) graphenecoupled Schiff-base hierarchically porous polymers (GS-HPPs). The method involves the polymerization of melamine and 1,4-phthalaldehyde, yielding Schiff-base porous polymers on the interconnected macroporous frameworks of 3D graphene aerogels. The as-synthesized GS-HPPs possess hierarchically porous structures containing macro-/meso-/micropores, along with large specific surface areas up to 776 m² g⁻¹ and high nitrogen contents up to 36.8 wt%. Consequently, 3D nitrogen-enriched hierarchically porous carbon (N-HPC) materials with macro-/meso-/micropores were obtained by the pyrolysis of the GS-HPPs at a high temperature of
800 °C under a nitrogen atmosphere. With a hierarchically porous structure, good thermal stability and a high nitrogen-doping content up to 7.2 wt%, the N-HPC samples show a high specific capacitance of 335 F g⁻¹ at 0.1 A g⁻¹ in 6 M KOH, a good capacitance retention with increasing current density, and an outstanding cycling stability. The superior electrochemical performance means that the N-HPC materials have great potential as electrode materials for supercapacitors
Food and feed trade has greatly impacted global land and nitrogen use efficiencies over 1961–2017
International trade of agricultural products has complicated and far-reaching impacts on land and nitrogen use efficiencies. We analysed the productivity of cropland and livestock and associated use of feed and fertilizer efficiency for over 240 countries, and estimated these countries’ cumulative contributions to imports and exports of 190 agricultural products for the period 1961–2017. Crop trade has increased global land and partial fertilizer nitrogen productivities in terms of protein production, which equalled savings of 2,270 Mha cropland and 480 Tg synthetic fertilizer nitrogen over the analysed period. However, crop trade decreased global cropland productivity when productivity is expressed on an energy (per calorie) basis. Agricultural trade has generally moved towards optimality, that is, has increased global land and nitrogen use efficiencies during 1961–2017, but remains at a relatively low level. Overall, mixed impacts of trade on resource use indicate the need to rethink trade patterns and improve their optimality
Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease
BACKGROUND:
Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes.
METHODS:
We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization.
RESULTS:
During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events.
CONCLUSIONS:
Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)